Digital to analog converters ("DACs") are electronic devices which generate an analog signal from a digital input. DACs serve to bridge the gap between digital signal processing and analog signal processing equipment in many areas including computer I/0 interfaces, lab test equipment and consumer goods such as compact disc players.
DACs convert their digital input to an analog output according to a mathematic transfer function. Linear, A-law companding and .mu.-law companding are three popular transfer functions known in the art which are widely accepted. Heretofore, DACs have converted data according to either (1) a linear transfer function, (2) one of the companding functions or (3) either of the companding functions as selected by the user. No known DAC has allowed a user to alternatively convert digital data into an analog output by a linear or by a companding transfer function. At least two devices have been required to perform all three conversion modes.
Therefore, a need has arisen for a DAC which is operable to convert digital data into an analog output by either a linear, A-law companding or .mu.-law companding transfer function.